create contact with lookup to account when account is craeted

5. Create a field on Account Named (Client Contact lookup to Contact). Once an Account is inserted a Contact will create with the name of the Account and that Contact will be the Client Contact on the Account.

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> when we want to create a field with lookup relation we want to create some empty list and Map
> list for contact to be updated
> list for account to be updated
> set for account to get the Id's from trigger.new
> map for checking the lookup relation between contact and account.

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Trigger contactOnAccountTrigger on Account (After Insert){
  switch on Trigger.OperationType{
   when AFTER_INSERT{
    contactOnAccountHelper.createContactOnAccount(Trigger.new);
   }
  }
}

Public with sharing class contactOnAccountHelper{
 public static void createContactOnAccount(List<Account> accList){
  if(accList != null){
   Set<Account> accSet = new Set<Account>();
   for(Account acc : accList){
      accSet.add(acc.Id);
   }
      List<Contact> conInserted = new contact();
   for( Account accContact : accList){
   contact con = new contact();
   con.LastName = accContact.name;
   con.accountId = accContact.Id;
   conInserted.add(con);
   accSet.add(con.AccountId);
   }
   if(conInserted.size() > 0 && conInserted != null ){
   INSERT conInserted;
   }
  }
  List<Account> accLkp = [SELECT id, name , Client_Contact__C from account where Id=: accSset];
  Map<Id, Account> accMap = new Map<Id, Account>();
  List<Account> accUpdated = new List<Account>();
  if(accLkp.size() > 0){
  for(Account acc: accLkp){
  accMap.put(acc.Id, acc);
  }
  }
  if(conInserted.size() > 0){
  for(Contact con: conInserted){
  if(accMap.containsKey(con.AccountId)){
  Account aObj = accMap.get(con.AccountId);
  accUpdated.add(aObj);
  }
  }
  }
  // check for the new account list to update.
  if(accUpdated.size() > 0 ){
  UPDATE accUpdated;
  }
 }
}